My brother's AMD 5600X CPU from 2021 had been throwing intermittent crashes since we had bought it. The more memory you run on it, or the quicker you clock it, the more frequently it crashes. He decided to RMA it when there weren't any games games coming out that he was interested in playing, and the shop ended up refunding him after AMD found a fault. I presume it's the memory controller on the chip.

So we bought a 5800X3D instead. It still threw the intermittent error when the RAM/infinity fabric was overclocked, with windows event viewer logging it as a CPU/memory channel? thing. So after that, I left the infinity fabric and memory on default.

A few days later, the PC resets and fails to POST. Motherboard diagnostic LED says "DRAM", but apparently that just means the PC encounters a fatal error as it tries to check the DRAM. Swapping out different kits of RAM didn't resolve the problem, and I can't reflash the BIOS without key components being operable.

So now I'm going through the RMA process again. Perhaps I got unlucky with AMD's memory controller lottery. Perhaps his board is frying CPUs (though the old chip didn't exactly get worse with time). We'll see.

I do have my own computer's mobo and CPU on the same platform that we could test, but mine is rock solid and I don't really feel like changing that.